diff --git a/.github/workflows/README.md b/.github/workflows/README.md
index f40f4cc86..3fad7e36f 100644
--- a/.github/workflows/README.md
+++ b/.github/workflows/README.md
@@ -43,10 +43,18 @@ I will provide the details of each workflow below.
 
 | Workflow Name          | File name                  | Description                                                                                                                                       |
 | ---------------------- | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `Build on PR`          | `build_on_pr.yml`          | This workflow is triggered when a PR changes essential files. It will run all the unit tests in the repository with 4 GPUs. |
+| `Build on PR`          | `build_on_pr.yml`          | This workflow is triggered when a PR changes essential files and a branch is created/deleted. It will run all the unit tests in the repository with 4 GPUs. |
 | `Build on Schedule`    | `build_on_schedule.yml`    | This workflow will run the unit tests everyday with 8 GPUs. The result is sent to Lark.                                                           |
 | `Report test coverage` | `report_test_coverage.yml` | This PR will put up a comment to report the test coverage results when `Build` is done.                                                           |
 
+To reduce the average time of the unit test on PR, `Build on PR` workflow manages testmon cache.
+
+1. When creating a new branch, it copies `cache/main/.testmondata*` to `cache/<branch>/`.
+2. When creating a new PR or change the base branch of a PR, it copies `cache/<base_ref>/.testmondata*` to `cache/_pull/<pr_number>/`.
+3. When running unit tests for each PR, it restores testmon cache from `cache/_pull/<pr_number>/`. After the test, it stores the cache back to `cache/_pull/<pr_number>/`.
+4. When a PR is closed, if it's merged, it copies `cache/_pull/<pr_number>/.testmondata*` to `cache/<base_ref>/`. Otherwise, it just removes `cache/_pull/<pr_number>`.
+5. When a branch is deleted, it removes `cache/<ref>`.
+
 ### Example Test
 
 | Workflow Name              | File name                       | Description                                                                    |
diff --git a/.github/workflows/build_on_pr.yml b/.github/workflows/build_on_pr.yml
index a5a17d176..b5f293107 100644
--- a/.github/workflows/build_on_pr.yml
+++ b/.github/workflows/build_on_pr.yml
@@ -2,7 +2,7 @@ name: Build on PR
 
 on:
   pull_request:
-    types: [synchronize, opened, reopened]
+    types: [synchronize, opened, reopened, ready_for_review, closed, edited]
     branches:
       - "main"
       - "develop"
@@ -18,11 +18,63 @@ on:
       - "!tests/**.md" # ignore doc change
       - "pytest.ini" # test config change
       - "setup.py" # install command change
+  create:
+  delete:
 
 jobs:
+  prepare_cache:
+    name: Prepare testmon cache
+    if: |
+      github.event_name == 'create' &&
+      github.event.ref_type == 'branch' &&
+      github.event.repository.full_name == 'hpcaitech/ColossalAI'
+    runs-on: [self-hosted, gpu]
+    container:
+      image: hpcaitech/pytorch-cuda:1.12.0-11.3.0
+      options: --rm
+    timeout-minutes: 5
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - name: Copy testmon cache
+        run: | # branch name may contain slash, we need to replace it with space
+          export REF_BRANCH=$(echo ${{ github.event.ref }} | sed "s/\// /")
+          if [ -d /github/home/testmon_cache/${MAIN_BRANCH} ]; then
+            [ ! -z "$(ls -A /github/home/testmon_cache/${MAIN_BRANCH})" ] && cp -p -r /github/home/testmon_cache/${MAIN_BRANCH} "/github/home/testmon_cache/${REF_BRANCH}"
+          fi
+        env:
+          MAIN_BRANCH: ${{ github.event.master_branch }}
+
+  prepare_cache_for_pr:
+    name: Prepare testmon cache for PR
+    if: |
+      github.event_name == 'pull_request' &&
+      (github.event.action == 'opened' || github.event.action == 'reopened' || (github.event.action == 'edited' && github.event.changes.base != null)) &&
+      github.event.pull_request.base.repo.full_name == 'hpcaitech/ColossalAI'
+    runs-on: [self-hosted, gpu]
+    container:
+      image: hpcaitech/pytorch-cuda:1.12.0-11.3.0
+      options: --rm
+    timeout-minutes: 5
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - name: Copy testmon cache
+        run: | # branch name may contain slash, we need to replace it with space
+          export BASE=$(echo ${{ github.event.pull_request.base.ref }} | sed "s/\// /")
+          if [ -d "/github/home/testmon_cache/${BASE}" ]; then
+            [ ! -z "$(ls -A "/github/home/testmon_cache/${BASE}")" ] && mkdir /github/home/testmon_cache/_pull && cp -p -r "/github/home/testmon_cache/${BASE}" /github/home/testmon_cache/_pull/${PR_NUMBER}
+          fi
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.head.ref }}
+
   detect:
     name: Detect file change
     if: |
+      github.event_name == 'pull_request' &&
+      (github.event.action == 'synchronize' || github.event.action == 'opened' || github.event.action == 'reopened' || github.event.action == 'ready_for_review') &&
       github.event.pull_request.draft == false &&
       github.event.pull_request.base.repo.full_name == 'hpcaitech/ColossalAI'
     outputs:
@@ -135,9 +187,11 @@ jobs:
 
       - name: Restore Testmon Cache
         run: |
-          if [ -d /github/home/testmon_cache ]; then
-            [ ! -z "$(ls -A /github/home/testmon_cache)" ] && cp -p -r /github/home/testmon_cache/.testmondata* /__w/ColossalAI/ColossalAI/
+          if [ -d /github/home/testmon_cache/_pull/${PR_NUMBER} ]; then
+            [ ! -z "$(ls -A /github/home/testmon_cache/_pull/${PR_NUMBER})" ] && cp -p -r /github/home/testmon_cache/_pull/${PR_NUMBER}/.testmondata* /__w/ColossalAI/ColossalAI/
           fi
+        env:
+          PR_NUMBER: ${{ github.event.number }}
 
       - name: Execute Unit Testing
         run: |
@@ -149,8 +203,10 @@ jobs:
 
       - name: Store Testmon Cache
         run: |
-          [ -d /github/home/testmon_cache ] || mkdir /github/home/testmon_cache
-          cp -p -r /__w/ColossalAI/ColossalAI/.testmondata* /github/home/testmon_cache/
+          mkdir -p /github/home/testmon_cache/_pull/${PR_NUMBER}
+          cp -p -r /__w/ColossalAI/ColossalAI/.testmondata* /github/home/testmon_cache/_pull/${PR_NUMBER}/
+        env:
+          PR_NUMBER: ${{ github.event.number }}
 
       - name: Collate artifact
         env:
@@ -188,3 +244,55 @@ jobs:
         with:
           name: report
           path: report/
+
+  store_cache:
+    name: Store testmon cache for PR
+    if: |
+      github.event_name == 'pull_request' &&
+      github.event.action == 'closed' &&
+      github.event.pull_request.base.repo.full_name == 'hpcaitech/ColossalAI'
+    runs-on: [self-hosted, gpu]
+    container:
+      image: hpcaitech/pytorch-cuda:1.12.0-11.3.0
+      options: --rm
+    timeout-minutes: 5
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - name: Store testmon cache if possible
+        if: github.event.pull_request.merged == true
+        run: | # branch name may contain slash, we need to replace it with space
+          export BASE=$(echo ${{ github.event.pull_request.base.ref }} | sed "s/\// /")
+          if [ -d /github/home/testmon_cache/_pull/${PR_NUMBER} ]; then
+            [ ! -z "$(ls -A /github/home/testmon_cache/_pull/${PR_NUMBER})" ] && cp -p -r /github/home/testmon_cache/_pull/${PR_NUMBER}/.testmondata* "/github/home/testmon_cache/${BASE}/"
+          fi
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+
+      - name: Remove testmon cache
+        if: github.event.pull_request.merged != true
+        run: |
+          rm -rf /github/home/testmon_cache/_pull/${PR_NUMBER}
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+
+  remove_cache:
+    name: Remove testmon cache
+    if: |
+      github.event_name == 'delete' &&
+      github.event.ref_type == 'branch' &&
+      github.event.repository.full_name == 'hpcaitech/ColossalAI'
+    runs-on: [self-hosted, gpu]
+    container:
+      image: hpcaitech/pytorch-cuda:1.12.0-11.3.0
+      options: --rm
+    timeout-minutes: 5
+    defaults:
+      run:
+        shell: bash
+    steps:
+      - name: Remove testmon cache
+        run: | # branch name may contain slash, we need to replace it with space
+          export BASE=$(echo ${{ github.event.ref }} | sed "s/\// /")
+          rm -rf "/github/home/testmon_cache/${BASE}"